Consequences of excessive scar formation: dealing with the problem and aiming for the future

Direct comparison of reproducibility and reliability in quantitative assessments of burn scar properties

INTRODUCTION

Determining the efficacy of anti-scar technologies can be difficult as qualitative, subjective assessments are often utilized instead of systematic, objective measures. Perceptions regarding the reliability of instruments for quantitative measurements along with their high cost and increased data collection time may discourage their use, leading to use of scar scales which are relatively quick and low-cost. To directly evaluate the reliability of instruments for quantitative measurements of scar properties, instruments and two qualitative scales were compared by assessing a variety of cutaneous scars.

METHODS

Scar height and surface texture were evaluated using a 3D scanner and a mold/cast technique. Scar color was evaluated by using a spectroscopy-based tool, the Mexameter®, and digital photography with image analysis. Scar biomechanics were evaluated using the BTC-2000™, Dermal Torque Meter (DTM®), and ballistometer®. The Vancouver Scar Scale (VSS) and Patient and Observer Scar Assessment Scale (POSAS) were used to qualitatively evaluate the same scar properties. Intraclass correlation coefficients (ICC) were used to determine inter- and intra-user reliability (poor, moderate, good, excellent) with all instruments and the kappa reliability statistic was used to asses inter-user reliability (poor, fair, moderate, good, very good) for VSS and POSAS. Time for measurement collection and after collection analysis was also recorded.

RESULTS

The Mexameter® was the most reliable method for evaluating erythema and pigmentation compared to digital photography and image processing, POSAS and VSS. Digital photography and analysis was more reliable than POSAS and VSS. Assessment of scar height was significantly more reliable when using a 3D scanner versus VSS and POSAS. The 3D scanner and mold-cast techniques also offered an additional benefit of providing an absolute value of scar height relative to the surrounding tissue. Intra-user reliability for all mechanical tests was moderate to good. Inter-user reliability was greater when using the BTC-2000™ and ballistometer® versus the DTM®. All quantitative measurements took less than 90 s for collection, with the exception of the mold/cast technique.

CONCLUSION

Non-invasive instruments allow scar properties to be quantitatively assessed with high sensitivity and as a function of time and/or treatment without the need for biopsy collection. Overall, the reliability of scar assessments was significantly improved when quantitative instruments were utilized versus scar scales. Quantitative assessment of color and biomechanics were swift, requiring less than 90 s per measurement while assessments of texture and height required additional analysis time after collection. With proper training of clinical staff and well-defined protocols for measurement collection, reliable, quantitative assessments of scar properties can be collected with little disruption to the clinical workflow.

Effect of Relaxin Expression from an Alginate Gel-Encapsulated Adenovirus on Scar Remodeling in a Pig Model

PURPOSE

Relaxin (RLX) is a transforming growth factor-β1 (TGF-β1) antagonist that is believed to function as a potent collagen re-arranger and a major suppressor of extracellular matrix components. Adenoviruses (Ads) are accepted vectors for cancer gene therapy. However, repeated treatments of Ad are limited by short-term biological activity in vivo. The efficacy of sustained RLX expression to scar remodeling was assessed using an injectable alginate gel-matrix system.

MATERIALS AND METHODS

Pig scar tissue was treated with relaxin-expressing Ad loaded in alginate gel (gel/Ad-RLX). Surface areas, color, and pliability of scars were compared, and various factors influencing scar formation and collagen arrangement were analyzed.

RESULTS

Gel/Ad-RLX decreased scar size, color index, and pliability. Immunohistochemistry showed decreased levels of major extracellular matrix proteins in the gel/Ad-RLX-treated group. Furthermore, treatment with gel/Ad-RLX reduced expression of tissue inhibitor of metalloproteinase-1 and alpha-smooth muscle actin and markedly increased expression of matrix metalloproteinase-1 in pig scar tissues. Gel/Ad-RLX also significantly downregulated TGF-β1 and upregulated TGF-β3 mRNAs in pig scar tissues.

CONCLUSION

These results support a prominent role for RLX in scar remodeling and suggest that gel/Ad-RLX may have therapeutic effects on scar formation.

Effect of Relaxin Expressing Adenovirus on Scar Remodeling: A Preliminary Study

Background

Relaxin is a transforming growth factor β1 antagonist. To determine the effects of relaxin on scar reduction, we investigated the scar remodeling process by injecting relaxin-expressing adenoviruses using a pig scar model.

Methods

Scars with full thickness were generated on the backs of Yorkshire pigs. Scars were divided into two groups (relaxin [RLX] and Control). Adenoviruses were injected into the RLX (expressing relaxin) and Control (not expressing relaxin) groups. Changes in the surface areas, color index and pliability of scars were compared.

Results

Fifty days after treatment, the surface areas of scars decreased, the color of scars was normalized, and the pliability of scars increased in RLX group.

Conclusion

Relaxin-expressing adenoviruses improved the surface area, color, and pliability of scars. The mechanism of therapeutic effects on scar formation should be further investigated.

A Comparison of Gene Expression of Decorin and MMP13 in Hypertrophic Scars Treated With Calcium Channel Blocker, Steroid, and Interferon: A Human-Scar-Carrying Animal Model Study

BACKGROUND

The formation of hypertrophic scaring (HSc) is an abnormal wound-healing response. In a previous study, an animal model with human scar tissue implanted into nude mice (BALB/c) has been successfully established. The effects of verapamil as well as combination therapy with verapamil and kenacort have been studied and compared.

OBJECTIVE

To treat persistent hypertrophic scars, local injection of drugs composed of steroids, calcium channel blockers (CCBs), and interferon might be a good method. What is the best dose of the regimen and what are the mechanisms are also a worthwhile study.

MATERIALS AND METHODS

Scar specimens were harvested from patients with HSc or Keloid resulting from burn injury, and then implanted to BALB/c-nu nude mice for 4 weeks. Before implantation, the specimen was either injected with or without drugs such as steroids (kenacort), CCBs (verapamil), and interferons (INFα2b), respectively. After the removal of implants, quantitative gene expressions of decorin and collagenase (MMP13) were measured using a real-time polymerase chain reaction to detect their mRNAs. Two way-ANOVA and Post Hoc were used for statistical analysis using the software SPSS 15.0.

RESULTS

All drug-treated groups increased the expressions of decorin and MMP13 in comparison with those in noninjected group (p < .001) in a dose-dependent manner. Comparing equal amounts of individual drugs, gene expression of decorin was increased with increasing injection amount, and the best result in low amount of injection (0.02 mL of each) was shown in the group injected with INFα2b followed by kenacort and verapamil. However, the results were changed while injection amount was up to 0.04 mL and the strongest decorin gene expression was found in kenacort injection. Regarding MMP-13 expression, low-amount injection (0.02 mL) of INFα2b has strongest gene expression followed by kenacort and verapamil, but in the large-amount regimes (0.04 mL), verapamil had strongest gene expression followed by INFα2b and kenacort.

CONCLUSION

This study showed that the kenacort, verapamil, and INFα2b all inhibited HSc in a dose-dependent manner through the evidence of gene expression of decorin and MMP13. In comparison with the injections between small amounts of drugs, INFα2b potentiated the strongest decorin and MMP13 expression. On the contrary, among the large-amount injection regimes, kenacrot was more effective on decorin expression as verapamil to MMP13 expression. To decrease side effects from the drugs and produce promising results for the clinical practice, it is suggested to maintain the dose of INFα2b along with an increased dose of verapamil for HSc improvement.

Human melanocytes mitigate keratinocyte-dependent contraction in an in vitro collagen contraction assay

Scarring is an extensive problem in burn care, and treatment can be especially complicated in cases of hypertrophic scarring. Contraction is an important factor in scarring but the contribution of different cell types remains unclear. We have investigated the contractile behavior of keratinocytes, melanocytes and fibroblasts by using an in vitro collagen gel assay aimed at identifying a modulating role of melanocytes in keratinocyte-mediated contraction. Cells were seeded on a collagen type I gel substrate and the change in gel dimensions were measured over time. Hematoxylin & Eosin-staining and immunohistochemistry against pan-cytokeratin and microphthalmia-associated transcription factor showed that melanocytes integrated between keratinocytes and remained there throughout the experiments. Keratinocyte- and fibroblast-seeded gels contracted significantly over time, whereas melanocyte-seeded gels did not. Co-culture assays showed that melanocytes mitigate the keratinocyte-dependent contraction (significantly slower and 18-32% less). Fibroblasts augmented the contraction in most assays (approximately 6% more). Non-contact co-cultures showed some influence on the keratinocyte-dependent contraction. Results show that mechanisms attributable to melanocytes, but not fibroblasts, can mitigate keratinocyte contractile behavior. Contact-dependent mechanisms are stronger modulators than non-contact dependent mechanisms, but both modes carry significance to the contraction modulation of keratinocytes. Further investigations are required to determine the mechanisms involved and to determine the utility of melanocytes beyond hypopigmentation in improved clinical regimes of burn wounds and wound healing.

Outcome after burns: an observational study on burn scar maturation and predictors for severe scarring

Long-term outcome of burn scars as well as the relation with clinically relevant parameters has not been studied quantitatively. Therefore, we conducted a detailed analysis on the clinical changes of burn scars in a longitudinal setup. In addition, we focused on the differences in scar quality in relation to the depth, etiology of the burn wound and age of the patient. Burn scars of 474 patients were subjected to a scar assessment protocol 3, 6, and 12 months postburn. Three different age groups were defined (≤5, 5-18, and ≥18 years). The observer part of the patient and observer scar assessment scale revealed a significant (p < 0.001) improvement in scar quality at 12 months compared with the 3- and 6-month data. Predictors for severe scarring are depth of the wound (p < 0.001) and total body surface area burned (p < 0.001). Etiology (p = 0.753) and age (p > 0.230) have no significant influence on scar quality when corrected for sex, total body surface area burned, time, and age or etiology, respectively.

Effect of human adipose derived stem cells on scar formation and remodeling in a pig model: a pilot study

BACKGROUND

Adipose-derived stem cells (ASCs) have positive effects in the wound healing process.

OBJECTIVE

To clarify whether ASCs positively mitigate scar formation in the wound remodeling process.

MATERIALS AND METHODS

Full-thickness skin defects were created on the dorsal skin of Yorkshire pigs. After the defects were transformed into early scars, ASCs were injected, and the same amount of phosphate buffered saline (PBS) was injected in the control group. Clinical and histologic examinations were performed.

RESULTS

In the experimental group, the areas of scars were smaller than those of control groups. The color of scars was more similar to that of the surrounding normal tissue, and scar pliability was better. The number of mast cells decreased, and more-mature collagen arrangement was noted. In the early period of scar remodeling, the expression of transforming growth factor beta (TGF-β)3 and matrix metalloproteinase 1 (MMP1) was greater in the experimental group than in control group. In the late period, the level of alpha smooth muscle actin and tissue inhibitor of metalloproteinase 1 were dramatically less, although the level of MMP1 was lower in the experimental group than in control group.

CONCLUSIONS

Local injection of ASCs decreases scar size and provides better color quality and scar pliability. It decreases the activity of mast cells and inhibits the action of TGF-β against fibroblasts and positively stimulates scar remodeling through greater expression of MMP molecules.

Scarless healing of oral mucosa is characterized by faster resolution of inflammation and control of myofibroblast action compared to skin wounds in the red Duroc pig model

BACKGROUND

Scar formation following skin trauma can have devastating consequences causing physiological and psychosocial concerns. Currently, there are no accepted predictable treatments to prevent scarring which emphasizes a need for a better understanding of the wound healing and scar formation process.

OBJECTIVES

Previously it was shown that healing of small experimental wounds in the oral mucosa of red Duroc pigs results in significantly reduced scar formation as compared with equivalent full-thickness skin wounds. In the present study, scar formation was assessed in 17 times larger experimental wounds in both oral mucosa and skin of the red Duroc pigs.

METHODS

Equivalent experimental wounds were created in the oral mucosa and dorsal skin of red Duroc pigs, and scar formation, localization and abundance of key wound healing cells, transforming growth factor-beta (TGF-beta) and phosphorylated Smad3 (pSmad3) were assessed.

RESULTS

Oral mucosal wounds displayed significantly less clinical and histological scar formation than did the corresponding skin wounds. The number of macrophages, mast cells, TGF-beta and pSmad3 immunopositive cells was significantly reduced in the oral mucosal wounds as compared with skin wounds during the maturation stage of the healing process. Although the number of myofibroblasts was significantly elevated, the oral mucosal wounds showed significantly less contraction than did the skin wounds over time.

CONCLUSIONS

Earlier resolution of the inflammatory reaction and reduced wound contraction may promote scarless oral mucosal wound healing. In addition, scar formation likely depends not only on the number of myofibroblasts but also on the extracellular environment which regulates their function.